1. Field of the Invention
The present invention relates to method for assembly of an LED lighting device which can be, for instance, a reading or seat light for use in a vehicle such as, e.g. an airplane, a train or a bus, and which comprises an LED module and an optical unit which can be of the reflective type (e.g. a reflector) and/or the refractive type (e.g. a lens).
2. Related Prior Art
The specification of lighting devices usually includes requirements with regard to brightness, color, and light distribution. Lighting devices comprise, apart from an illuminant, also optical systems; to be counted among these are reflectors and/or lenses, for instance. Optical systems should be as small-sized as possible so that the lighting device can be designed to have a small constructional depth.
As illuminants for reading or seat lights in vehicles such as, e.g., airplanes, increasing use is made of LEDs because of their easy maintenance and their long useful life.
In many commercially available LEDs, the dies have relatively large positional tolerances, particularly in the direction of the optical axis. Also the optical systems used for the lighting devices are subject to tolerances with respect to their position, their shape and their optical characteristics, notably under the aspect of efficiency, gloss level and imaging accuracy.
In optoelectronic systems for the coupling of electromagnetic radiation of an LED or laser diode into an optical fiber, it is known to displace the fibers along their axes relative to the LED and respectively laser diode until the coupled-in radiation intensity will correspond to a preset value. Examples thereof are found in FR-A-2 767 928, U.S. Pat. No. 4,237,474, U.S. Pat. No. 4,500,165 and U.S. Pat. No. 5,177,807. These known systems, however, are not suited for the assembly process of LED lights provided for illumination of surfaces or spaces, as is the case in reading or seat lights for use in a vehicle such as, e.g. an airplane, a train or a bus.
It is an object of the invention to improve the assembly process for LED lights to the effect that the parts-reject rate is reduced.